1. Field of the Invention
The present invention relates to an input pen for a portable information processing terminal device, such as a PDA (personal digital assistant).
2. Description of the Related Art
An input pen employed in operating a conventional portable information processing terminal device is provided with an input tip and a tip return spring biasing the input tip forward so that the input pin is able to move backward when an excessively high pressure is applied to the input tip.
The pressure of the tip return spring, however, cannot be adjusted to adjust the force biasing the input tip longitudinally forward according to the purpose of the input pen.
Another input pen employed in a conventional portable information processing terminal device is provided with a ballpoint refill in a barrel. The replacement of the ballpoint refill contained in the barrel having a small inside diameter with another one requires very troublesome work.
It is an object of the present invention to provide an input pen capable of solving problems in the conventional input pen.
To achieve the object, according to one aspect of the present invention, an input pen for a portable information processing terminal device includes a barrel, a front barrel detachably attached to a front portion of the barrel, an input tip axially slidably fitted in the front barrel, and a return spring placed in the front barrel to apply pressure to the input tip so as to bias the input tip forward, wherein the pressure applied to the input tip by the return spring is optionally adjustable.
Since the pressure of the return spring can be optionally adjustable according to the user""s preference, the input pen can be operated for input operations in an optimum condition.
According to another aspect of the present invention, an input pen for a portable information processing terminal device includes a barrel, an input tip fitted in a front portion of the barrel, a reset pin detachably attached to a front portion of the barrel, and a ballpoint refill having a writing part and detachably mounted on the reset pin, and a cap detachably put on the barrel so as to cover the writing part of the ballpoint refill. The used ballpoint refill can be replaced with a new one simply by removing the reset pin from the barrel, removing the used ballpoint refill from the reset pin and putting the new ballpoint refill on the reset pin.